Dr. Freeman is an Assistant Professor of Psychiatry at the University of Arizona and Director of the Women's Mental Health Program of the Department of Psychiatry. After receiving her M.D. from Northwestern University Medical School, she completed a psychiatry residency at the Harvard Longwood Psychiatry Residency Training Program and a Fellowship in Biological Psychiatry at the University of Cincinnati. Her immediate goals are: I) to obtain proficiency in clinical research methodology, with specific emphasis on gender-specific psychopharmacologic research, statistics, and ethical issues, and 2) to gain expertise in the research on mood disorders during pregnancy and the postpartum period. Long term goals are: 1) to become an independent investigator of mood disorders during pregnancy and postpartum, 2) to obtain an ROI award to support further study as an independent investigator, and 3) to serve as a mentor for junior investigators. The career development plan includes a structured didactic program designed to facilitate development to an independent investigator. Mentorship includes work with a primary mentor, Alan Gelenberg, M.D., and strong mentorship in the areas of women's psychiatry and omega-3 fatty acids. A multidisciplinary Advisory Committee will oversee the career development activities at the University of Arizona. The proposed research study is a double-blind, placebo-controlled 3-arm trial of omega-3 fatty acids (FA) in postpartum depression. Data suggest omega-3 fatty acids are efficacious in the treatment and prophylaxis of major depressive disorders. Omega-3 fatty acids may be especially relevant in the treatment of postpartum depression, due to the depletion of maternal omega-3 fatty acids that occurs during pregnancy. The purpose of this study is to determine the efficacy, as well as most effective dose, of omega-3 fatty acids for postpartum depression. Two omega-3 fatty acids in fish oil are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Two different active arms are included in this protocol, one in which patients receive 2.8 g of EPA plus DHA (1.7 g EPA and 1.1 g DHA) and another in which patients receive I g EPA. The active arms were carefully chosen on the basis of pilot treatment data and epidemiological data; they should produce optimal tissue levels. These doses should provide an adequate test of the efficacy of omega-3 fatty acids while being safe for the mother and breastfeeding baby.